Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

416
FXUS63 KLOT 301606
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1006 AM CST Fri Jan 30 2026

.KEY MESSAGES...

- Cold conditions will continue into the weekend with mainly
  subzero wind chills through Saturday morning.

- Central and southern Cook County were upgraded to a Winter
  Storm Warning (replacing previous advisory) and is in effect
  until midnight tonight for periods of heavy/intense lake
  effect snow through this evening. Hazardous travel conditions
  are expected closer to the lake in Illinois today as waves of
  lake effect snow continue. Light snow with occasional bursts
  of moderate snow farther inland in northern Illinois will
  cause localized hazardous travel.

- Significant snowfall accumulations and very hazardous travel
  are likely near the lake in northwest Indiana tonight into
  Saturday, with the potential for additional notable
  accumulations and travel impacts in Cook and eastern Will
  counties east of I-57 late tonight through Saturday morning.

- There may be a period of light snow accumulations Sunday
  night into Monday, followed by less cold conditions by
  midweek.

&&

.UPDATE...
Issued at 1006 AM CST Fri Jan 30 2026

As generally anticipated, the mid-level and surface trough axis
configuration today is decidedly focusing lake effect snow
banding near and on the west side of the lake. However, the
intensity of the snow extending well north to offshore of
Manitowoc, WI increases concern for bursts of moderate to heavy
lake effect snow persisting into this evening for northeast
Illinois. While this won`t be a continuous firehose of snow
like in a single dominant intense band, webcams under the
heavier snow rates have consistently shown roads quickly
becoming snow covered/hazardous.

With the previous advisory and watch configuration for central
and southern Cook, there was some thought that there would be
more defined breaks in the accumulating snow, which appears less
likely at this point. Additionally on this note, comparing radar
to recent HiRes simulations, the HRRR seems to have a better
handle than the 12z NAMnest (which initialized too far east with
the snow off the WI shore). This suggests the intense banding
developing this evening has a better chance to impact eastern
sections of Cook County (and possibly even Lake and northern
Cook) before shifting into northwest Indiana tonight.
Ultimately, we opted to just replace the previous advisory for
central and southern Cook with a warning, in effect until
midnight. Confidence isn`t super high in exact trends yet, but
felt that localized 6"+ amounts appear quite likely (especially
near the lake), and more importantly the significant impacts to
travel due to periods of 1-2"/hour snow rates and visibility as
low as 1/4 mile.

We`re keeping a close eye on webcams and road conditions in
Lake and northern Cook as well (Waukegan Airport 1/4 mile
visibility as of this writing) for a possible need to upgrade
these counties from an advisory to a warning. As the snow
band(s) come ashore today, convective snow showers may spread
fairly far inland into areas where broad light snow is ongoing
underneath the mid/upper trough. Should it appear this activity
is more potent, we may need to consider advisories for this, or
at least Special Weather Statement issuance. The Winter Storm
Warnings for Lake and Porter County Indiana remain unchanged for
now. DuPage County IL is also in an advisory given the closer
proximity to the lake of northeastern sections of the county,
though again, confidence is on the lower side regarding how
things will play out farther inland in the Chicago suburbs.

Castro/KJB

&&

.DISCUSSION...
Issued at 343 AM CST Fri Jan 30 2026

Through Saturday:

Several periods of primarily lake effect snow will result in
locally higher snowfall rates and hazardous travel near Lake
Michigan in northeast Illinois and northwest Indiana today
through Saturday. There are three distinct periods of focus
during this time:

1) Today: A surface trough will shift SSW across northern
Illinois through the day as a mid-level convergent/LES axis
drifts westward into northeast Illinois. Surface analysis
indicates the existence a hybrid meso-low and small
thermal/synoptic low over southern Lake Michigan early this
morning. Some CAMs have picked up on this feature, which favor
an enhanced east to west convergent axis on the northern edge of
the low as it backs into northeast Illinois through the day. So
while an initial LES push will bring a period of briefly poor
travel conditions late this morning into the afternoon, a more
focused lake-enhanced band of snow may settle near the IL/WI
line for several hours late this morning into the mid-afternoon.

2) Tonight: Broader synoptic flow will back slightly with time
as the mid-level trough moves south and east, allowing a
developing dominant LES band or broken/braided band over western
Lake Michigan to shift southward along the Illinois shore and
into northwest Indiana this evening. Steepening low-level lapse
rates with a reinforcing shot of colder air combined with
inversion heights up to 8-9kft should result in intense snowfall
rates of 1 to 2"+ per hour with this band. While residence time
of the band at a given location in northeast Illinois will be
under two hours, conditions will likely become very hazardous
during this time. The band should wobble back and forth over
northwest Indiana late evening into the overnight hours with
continued intense snowfall rates. Very dangerous travel is
possible over northern Lake and/or Porter counties tonight, with
increasing N/NNW winds resulting in localized blowing and
drifting snow.

3) Saturday: Synoptic flow will begin to veer N or even NNE
(especially at 925 hPa and above) as inversion heights slowly
lower under 6kft. There is a window during the morning when the
dominant band should settle around the IL/IN state line when
thermo profiles are still quite favorable. Rates of 1-2"/hr will
be possible during this time, particularly with much of the LES
convective layer in the DGZ.

When all is said and done, locations along Porter and Lake
County IN will likely see totals in excess of 6", with some
locations in excess of 12" not out of the question. Farther
west, totals may exceed 6" over southeast portions of Chicago
and into the south suburbs east of I-57.

Headlines: With the potential for LES to be more focused into
far northeast Illinois into this afternoon, have extended the
Winter Weather Advisory for all original counties to 00Z. Gave
some thought to including McHenry and Kane with the expected
convergent axis possibly residing well inland for several hours
this afternoon, but confidence in higher impacts were too low at
this time. The headline for Central/Southern Cook was a bit
tricky, as advisory-level impacts are expected in all three
windows noted above. However, there will be gaps between each
window. Had to decide between an extended advisory, or maintain
the watch and extend it into Saturday. With the potential for
the intense LES backing into Chicago by daybreak Saturday, felt
the watch was the path of least regret at this time. Otherwise,
the Winter Storm Warning for Lake/Porter was left unchanged,
while an advisory was added to eastern Will due to farther
inland extent of the dominant band.

Kluber


Saturday Night through Thursday:

Active northwest flow will continue beyond this weekend`s
system and into next week, and will guide several disturbances
across the general region through next week. Medium range
guidance continues to resolve the first of these waves scooting
across the Upper Midwest and Great Lakes region sometime during
the Sunday PM - Monday timeframe. In general, large scale height
falls don`t appear all that impressive, with the main surface
trough and associated low forecast to slide well to our north.
However. fairly robust DCVA on the southern flanks of this
feature, coupled with north-south transient bands of mid-level
f-gen may be sufficient to crank out some light snowfall over
parts of the area, particularly the closer to the Wisconsin
state line you get. The fairly quick forward progression of this
system, as well as a general lack of deeper moisture, suggests
snowfall amounts will be light, probably limited to a few tenths
to an an inch or so. Based on the latest guidance trends, it`s
possible dry air plays a role and ultimately limits snowfall
chances with this feature as well.

Deterministic and ensemble guidance spread increases markedly
after Tuesday, lowering overall forecast confidence during the
middle and end of next week. With a lingering baroclinic zone
just to our south, there`s a potential for some continued
precipitation chances even into Tuesday/Wednesday, but this is
far from ubiquitous across the guidance suite.

While below normal temperatures are expected to continue into
early next week, there` a decent model signal for at least a
moderating trend during the middle and end of the week, with
highs potentially pushing near and above freezing.

KJB/Carlaw

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 522 AM CST Fri Jan 30 2026

Primary aviation concerns:

* Periods of lake effect snow are expected today through
  Saturday, impacting ORD/MDW/DPA and possibly RFD today, GYY
  tonight, and GYY/MDW again tomorrow morning.

A band of lake effect snow with embedded mesolows of varying
scale over Lake Michigan will swing into northeastern Illinois
this morning, first reaching ORD/MDW at around 16Z and then DPA
at around 17Z, and possibly as far inland as RFD by 19Z. Winds
will turn from northwest to northeast as the band moves
overhead. The band should then transition into a broad region of
snow showers at least in the vicinity of if not directly over
ORD/DPA/MDW this afternoon. The region of snow showers will
gradually shift southeastward through the afternoon and reach
GYY sometime after 00Z. Visibility in the snow showers this
morning and afternoon will be poor, ranging from 1/4 to 3/4 of a
mile. Snow rates of 1 to locally 2 inches per hour will lead to
quick coats of snow on runways, as well. Snow is not expected
to be continuous all day at any given terminal. By 01 to 02Z,
the lake effect snow is expected to be east of DPA/ORD/MDW,
giving way to broken MVFR cigs and northwesterly winds of around
10 kt.

Forecast confidence in the exact evolution of the lake effect
snow band overnight is somewhat low, with plausible scenarios
ranging from a somewhat disorganized snow bands pivoting as far
west as Gary to as far east as Benton Harbor, to a single,
dominant band parked over the same location all night. In the
latter scenario, visibility could very well fall below 1/4 of a
mile for a prolonged period of time. Will go ahead and advertise
such low conditions as a TEMPO group at GYY as the initial band
swings overhead this evening (slightly higher confidence), and
then carry a PROB30 group overnight in deference to different
forecast scenarios.

Toward the end of the TAF period, the lake effect snow band is
expected to whip back westward toward the Illinois shoreline,
potentially as far west as MDW. So, will introduce a PROB30
group focused in the latter 6 hours of the 30-hour TAF window.

Borchardt

&&

.HYDROLOGY...
Issued at 230 PM CST Wed Jan 28 2026

River gauges, reports from local officials, and reports from
trained ice spotters continue to indicate a few ice jams across
the area due to the significant increase in river ice over
recent days. With continued cold weather into next week,
conditions will remain favorable for river ice formation. While
no widespread flooding is expected, localized ice jams may
occur.

- NWS Chicago

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Winter Weather Advisory until 6 PM CST this evening for ILZ006-
     ILZ013-ILZ103.

     Winter Storm Warning until midnight CST tonight for ILZ104-
     ILZ105.

     Winter Storm Watch from late tonight through Saturday morning
     for ILZ104-ILZ105.

     Winter Weather Advisory from 6 PM this evening to noon CST
     Saturday for ILZ108.

IN...Winter Storm Warning from 3 PM this afternoon to 6 PM CST
     Saturday for INZ001-INZ002.

LM...Small Craft Advisory until 9 PM CST Saturday for Winthrop
     Harbor IL to Gary IN.

     Small Craft Advisory from 6 PM this evening to 3 AM CST Sunday
     for Gary to Burns Harbor IN-Burns Harbor to Michigan City
     IN.

&&

$$

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